Scanning exposure slit for a shuttle style film gate

ABSTRACT

An exposure slit is provided for a shuttle style film gate in a film transport. The exposure slit is provided on a plate that is mounted to the film gate shuttle. After the shuttle advances a frame of the film, it carries the slit with it during its return to a home position. Exposure of the film frame is made through the slit during the return travel.

BACKGROUND OF THE INVENTION

The present invention relates to apparatus for imaging photographic film or the like, and more particularly to a scanning exposure slit for a shuttle style film gate used in a film transport. As used herein, the term "film" is intended to mean any type of image recording medium, including photographic film, thermal media, dye transfer media and the like, and is not to be construed only as photographic firm.

In order to record high quality images on photographic film or other media for the production of movies or slides, film recorders are used. In a conventional film recorder, a light beam from a cathode ray tube ("CRT") or the like is controlled by a deflection system to scan across a stationary frame of photographic film to expose the film with an image. Typically, the images are generated by a computer for the production of slides, transparencies, photographs or the like. Alternatively, the images can comprise natural images acquired by a scanner or television camera for subsequent processing by a computer.

Known film recorders, such as those sold under the trademark SOLITAIRE® by Management Graphics, Inc. of Minneapolis, Minn., U.S.A., typically include a light source such as a CRT for producing a beam, a deflection system for scanning the beam across the face of the CRT, a system control and central processor unit ("CPU") for controlling the deflection system, and a camera (i.e., "film transport"). The later component may include a film transport body, lens, lens mounting assembly, aperture plate, film plate, and film transport mechanism. One type of film transport mechanism that is widely in use is a shuttle style film gate. Such transports are manufactured, for example, by Oxberry Corporation of Mamaroneck, N.Y., U.S.A.

On a Solitaire® film recorder, an image to be recorded is first written on the phosphor of the CRT by deflecting an electron beam in a raster pattern and modulating the intensity of the beam. This process is analogous to the creation of a television picture. Alternatively, the image can be written on the CRT using well known time modulation techniques, wherein the beam intensity is constant but the time the beam is kept at each point is varied depending on the exposure required.

The resulting pattern (the "object image") on the CRT is optically imaged onto photographic film by the film transport, which contains the required optics and mechanism to advance the film to successive frames. Other types of light sources can be substituted for the CRT in a film recorder. Examples include fiber optic sources, lasers and focused light impinging a rotating drum wherein one or more rotations are completed for each scan line.

One problem that has arisen when light is scanned onto the film one line at a time is that the light for one line will bleed over into other lines. This results in fogging of the image or a halo effect that is detrimental to the final image.

In a shuttle style film gate, such as that used in the aforementioned Oxberry film transport, successive frames of film are moved into an exposure area one at a time. The film is transported through the exposure area using pins which engage sprockets on the film. The pins pick up the film at one end of the exposure area and transport it to the other end, where the new frame is then lowered (or raised) onto fixed pins which precisely register the frame for exposure. During exposure, the moving pins are returned to the first end of the exposure area where they will be ready to pick up the film after exposure of the current frame, in order to transport the next successive frame into position for exposure. The moving pins can be driven by a stepper motor, which can be controlled by an electronic controller (e.g., CPU) in order to properly synchronize the film transport and exposure operations.

It would be advantageous to provide such a shuttle style film gate with a mechanism for reducing the fog and halo effects which result when light from one line being scanned bleeds over into other lines. It would be further advantageous to provide such a mechanism that can be fitted onto a conventional shuttle style film gate with minimal modification. It would be still further advantageous to provide such a mechanism that takes advantage of the motion already provided by the film gate in order to overcome the problems of fog and halo.

The present invention provides a scanning exposure slit mechanism having the aforementioned and other advantages.

SUMMARY OF THE INVENTION

In accordance with the present invention, a shuttle style film gate of a film transport is improved by providing an exposure slit. The film gate has at least one first pin for releasably transporting film across an exposure aperture of the film gate and at least one second pin that is independent of the first pin for releasably holding a frame of the film in registration adjacent the aperture for exposure by an imaging source. The first pin extends from a shuttle member that is driven in a first direction from a starting point to advance the film through the film gate. The shuttle member is driveable in a second direction opposite to the first direction to return to the starting point while the film is held by the second pin. The improvement comprises a plate extending from the shuttle member for movement therewith. The plate has an exposure slit arranged therein to pass between the aperture and the imaging source when the shuttle is driven in the second direction. In this manner, the film frame can be exposed by a beam from the imaging source passing through the slit as the slit moves across the frame in the second direction.

In an illustrated embodiment, the shuttle comprises a fork that rides on a motor-driven cam for reciprocal motion along the first and second directions. The plate is mounted to the fork for extension away from the cam in a third direction perpendicular to the first and second directions. In this embodiment, the first pin is mounted to a transport arm that extends from the fork in the third direction. The plate and transport arm overlap in respective first and second planes that are parallel to one another with the exposure aperture between them. The exposure aperture defines an image plane that is parallel to the first and second planes. The slit extends longitudinally in the third direction.

The shuttle is driven by a motor, such as a stepper motor. Control means are coupled to the motor and the imaging source for synchronizing the movement of the exposure slit and the beam in the second direction as the film frame is being exposed. The imaging source can comprise, for example, a slow scan CRT film recorder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an image recorder having a film transport mounted thereon;

FIG. 2 is a perspective view of a shuttle style film gate which has been modified in accordance with the present invention;

FIG. 3 is an exploded perspective view of a shuttle and exposure slit assembly in accordance with the present invention;

FIG. 4 is a simplified bottom plan view of the film gate assembly as modified in accordance with the present invention;

FIG. 5 is a cross-sectional view of the film gate assembly of FIG. 2:

FIGS. 6A to 6D are diagrammatic illustrations showing the operation of the film gate in accordance with the present invention; and

FIG. 7 is a schematic illustration of control means for the modified film gate in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an exposure slit for a shuttle style film gate. Such film gates are found, for example, in film transports used in combination with computerized image recorders. Such a combination, generally designated 10 in FIG. 1, comprises an image recorder 14 and a film transport 12. The purpose of the film transport is to carry photographic film or a similar recording medium that is to be exposed (i.e., imaged) by the image recorder, and to properly place each successive frame of the recording medium into registration with the image recorder optics for exposure. The film transport 12 includes a shuttle style film gate 16 which is removably mounted to a mounting plate 69.

The film gate 16 is illustrated in greater detail in FIGS. 2-5. The purpose of the film gate is to transport recording medium 20 over an aperture 64 (best shown in FIGS. 4 and 5) one frame at a time. The film gate must precisely register each successive frame over the aperture so that proper exposure of the film can be made. Precise registration is accomplished through a plurality of fixed registration pins 26, shown in FIG. 5. The fixed registration pins engage sprocket holes 22 in the recording medium 20.

Within the film gate, the recording medium travels between top and bottom gate elements 70a, 70b, respectively. These gate elements are mounted for movement away from and towards the aperture 64 via a lifting mechanism 30 which, in turn, is raised and lowered by the action of a cam follower 28 riding on a cam surface 32 of cam 18. The raising and lowering of lifting mechanism 30 is guided at the outboard edge of the film gate by a guide pin 38 that rides in slot 39 of support plate 40.

When the film gate elements 70a, 70b are lifted away from the aperture 64, the sprocket holes 22 of the recording medium carried therebetween are lifted off of the fixed registration pins 26. As a result, the recording medium is free to slide in a lengthwise direction between elements 70a, 70b. In order to advance the recording medium for the exposure of the next frame, moving pins 24 are provided to engage the sprocket holes 22 when the recording medium is lifted off of the fixed pins 26.

The moving pins 24 extend from a shuttle member generally designated 60 (FIG. 3) which comprises a fork portion 36 and a transport arm 42. The transport pins 24 extend from transport arm 42 and move with the transport arm back and forth in the lengthwise direction of the recording medium when the fork 36 is driven by lobe 34 of cam 18. The shuttling motion of the transport arm 42 is restricted to the lengthwise direction of the recording medium by the provision of bearing 44 on fork 36 which rides on shaft 46 (FIGS. 2, 4) of the film gate assembly. The shaft 46 is mounted to the assembly via mounts 48.

The rotation of cam 18, and thereby lobe 34 will cause the shuttle member 60 to transport the recording medium 20 from the left side of the film gate toward the right side thereof, from the viewpoint of FIG. 2, via pins 24 which engage sprocket holes 22 of the recording medium. The positions of lobe 34 and cam surface 32 are arranged such that the lifting mechanism 30 will lift the film gate elements 70a, 70b upwardly so that corresponding sprocket holes 22 will engage transport pins 24 when the transport arm 42 is on the left side of the film gate. After the transport arm 42 has shuttled to the right, pulling the recording medium with it, lifting mechanism 30 will lower the film off of the transport pins 24 and on to the fixed pins 26. The transport arm 42 is then free to return to its leftmost position, together with the rest of the shuttle member 60 while the recording medium is being imaged. In other words, the transport arm 42 will move the recording medium from the left to the right when pins 24 engage corresponding sprocket holes 22, and will be free to return to the left without moving the recording medium when the recording medium has been lowered onto the fixed registration pins 26.

In accordance with the present invention, a plate 50 is mounted to the conventional shuttle member 60. Plate 50 includes an exposure slit 52 that will move with the transport arm 42. In the specific embodiment shown, plate 50 is mounted directly to the fork portion 36 of the shuttle member 60 via screws 54. The plate 50 is bent at a 90° angle to provide a mounting portion 56 for this purpose.

In order to accommodate the plate 50 in an otherwise conventional film transport, a portion of mounting plate 69 is machined to provide a channel 68 on which the outer lip 50a of the plate 50 rides. This is most clearly illustrated in FIG. 2. If desired, the surface 68 can be coated with a material such as teflon to facilitate the movement of the lip 50a thereacross.

The transport of the recording medium across the film gate and the exposure thereof via slit 52 is illustrated schematically in FIGS. 6A to 6D. FIG. 6A illustrates the film gate elements 70a and 70b in an upper position, with the recording medium 20 therebetween. In the upper position, transport pins 24 extending from transport arm 42 engage corresponding sprocket holes 22 in the recording medium. The recording medium is not constrained by fixed pins 26. Thus, the transport arm 42 is free to pull the recording medium to the right, as illustrated by arrows 84 in FIG. 6B.

After the transport arm has pulled the recording medium to the right, the film gate elements 70a, 70b with the recording medium therebetween are lowered in the direction indicated by arrow 86 (FIG. 6C) so that corresponding sprocket holes in the recording medium will engage fixed pins 26. At this point, transport pins 24 will no longer engage any sprocket holes in the recording medium. The transport arm is therefore free to move (together with the rest of the shuttle member 60) in the direction of arrow 88 (FIG. 6D) where the transport pins 24 will be in a position to receive the recording medium for the next transport cycle.

When the recording medium is lowered against aperture 64 and held in a fixed position by fixed pins 26, the current frame thereof is ready to be exposed via a beam (e.g., a CRT beam) from the image recorder 14 (FIG. 1). In order to reduce undesirable effects such as flare, halo or fogging, the exposure slit 52 of the present invention limits the area of the recording medium exposed at any one time to a narrow slit.

In order to expose the recording medium, the beam 82 is scanned from point A to point B shown in FIG. 6C. During the exposure of the recording medium, transport arm 42 is returning from its position adjacent point A shown in FIG. 6C to the position adjacent point B illustrated in FIG. 6D. Since the exposure slit provided in accordance with the present invention is carried on plate 50 which is mounted to the shuttle member 60, it will be carried from point A to point B together with the transport arm 42. Thus, exposure slit 52 tracks in the same direction and at the same time as exposure beam 82.

Proper synchronization of the exposure slit and the beam from the image recorder is easily accomplished by controlling the image recorder deflection system and the film transport stepper motor. Such a control system is illustrated schematically in FIG. 7. Motor 90 is the stepper motor which controls the film gate cam 18 via shaft 100 as shown in FIG. 5. As the motor turns, the shuttle member 60 will carry the plate 50 and slit 52 under the aperture 64. This is clearly seen in the bottom view of FIG. 4, which shows how plate 50 tracks across the bottom wall 62 of the aperture assembly during the rotation of cam 18.

A controller 92 (FIG. 7) synchronizes the rotation of stepper motor 90, and thereby cam 18, with the deflection of the image recorder CRT 96 via deflection circuitry 94. The controller function can be provided, e.g., by the CPU that is already present in the image recorder. The stepper motor is incremented at whatever rate is necessary to enable the exposure slit to track the exposure beam along the frame being exposed.

The beam 82, which is projected through optics 98, is scanned back and forth along the length of the slit to expose the recording medium. After the exposure has been completed, transport arm 42 will be in the proper position to enable pins 24 to receive the recording medium and advance it to the next frame for exposure. The same sequence of operation will continue for each successive frame, with the exposure slit 52 being carried by the return of the transport arm 42 in the proper direction to enable exposure of the recording medium therethrough.

It should now be appreciated that the present invention provides an advantageous improvement for a shuttle style film gate. An exposure slit is provided with only minor modification to the film gate, to improve exposure accuracy. The slit is carried by the normal movement of the shuttle member, while remaining synchronized with the image recorder beam path.

Although the invention has been described in connection with a preferred embodiment thereof, those skilled in the art will appreciate that numerous adaptations and modifications may be made thereto without departing from the spirit and scope of the invention as set forth in the claims. 

What is claimed is:
 1. In a shuttle style film gate for a film transport having at least one first pin for releasably transporting film across an exposure aperture of said film gate and at least one second pin that is independent of said first pin for releasably holding a frame of said film in registration adjacent said aperture for exposure by an imaging source, said first pin extending from a shuttle member that is driveable in a first direction from a starting point to advance said film through said film gate and is driveable in a second direction opposite to said first direction to return to said starting point while said film is held by said second pin, the improvement comprising:a plate extending from said shuttle member for movement therewith, said plate having an exposure slit therein arranged to pass between said aperture and said imaging source when said shuttle member is driven in said second direction; wherein said film frame can be exposed by a beam from said imaging source passing through said slit as said slit moves across said frame in said second direction.
 2. A film gate in accordance with claim 1 wherein:said shuttle member comprises a fork that rides on a motor driven cam for reciprocal motion along said first and second directions; and said plate is mounted to said fork for extension away from said cam in a third direction perpendicular to said first and second directions.
 3. A film gate in accordance with claim 2 wherein:said first pin is mounted to a transport arm that extends from said fork in said third direction; and said plate and transport arm overlap in respective first and second planes that are parallel to one another with said exposure aperture therebetween.
 4. A film gate in accordance with claim 3 wherein said exposure aperture defines an image plane that is parallel to said first and second planes.
 5. A film gate in accordance with claim 4 wherein said slit extends longitudinally in said third direction.
 6. A film gate in accordance with claim 3 wherein said slit extends longitudinally in said third direction.
 7. A film gate in accordance with claim 2 wherein said slit extends longitudinally in said third direction.
 8. A film gate in accordance with claim 1 further comprising:a motor for driving said shuttle member; and control means coupled to said motor and said imaging source for synchronizing the movement of said exposure slit and said beam in said second direction as said film frame is being exposed.
 9. A film gate in accordance with claim 8 wherein said shuttle member is driven by said motor via a cam.
 10. A film gate in accordance with claim 8 wherein:said shuttle member comprises a fork that rides on said cam for reciprocal motion along said first and second directions; and said plate is mounted to said fork for extension away from said cam in a third direction perpendicular to said first and second directions.
 11. A film gate in accordance with claim 10 wherein:said first pin is mounted to a transport arm that extends from said fork in said third direction; and said plate and transport arm overlap in respective first and second planes that are parallel to one another with said exposure aperture therebetween.
 12. A film gate in accordance with claim 11 wherein said exposure aperture defines an image plane that is parallel to said first and second planes.
 13. A film gate in accordance with claim 12 wherein said slit extends longitudinally in said third direction.
 14. A film gate in accordance with claim 8 wherein said imaging source is a slow scan CRT film recorder. 